To combat climate change, cities need to tackle sprawl

Today’s new IPCC report, Climate Change and Land, contains extensive insight into how our stewardship of land impacts the environment. Deforestation, unsustainable agricultural practices, drought, and rising temperatures are interconnected, the report shows—and rapid, large-scale change is essential to preventing the worst impacts of the climate crisis.

The report also makes clear that living within our means doesn’t just mean cutting carbon emissions. Humans have to change how we oversee, develop, and interact with land. And part of that effort can start with cities, and specifically with the way cities encourage or discourage density and affordable housing.

The speed of sprawl

Consider the rapid growth of exurban areas of the United States, where developers continue to plow under farmland in an effort to build affordable homes. The country has lost 24 million acres of natural land in the last 16 years, according to the Center for American Progress, due in part to housing sprawl. That’s the equivalent of nine Grand Canyon National Parks. In the midwest and south, the encroachment of cities and development on natural lands was the most pronounced; in that same 16 year period, developed land area increased 47 percent in the midwest and 59 percent in the south.

That’s why the upzoning of Minneapolis, which made headlines for breaking the monopoly single-family home-only neighborhoods have on the urban landscape, made explicit mention of the environmental benefits of density. Building up instead of out is a key way for cities to commit to a more sustainable future.

That rapid rate of development and sprawl isn’t unique to the U.S. The IPCC estimates human use “directly affects more than 70 percent of global, ice-free land surface,” and that agriculture, deforestation, and the development of wetlands account for 23 percent of all human-caused greenhouse gas emissions. At the same time, 70 percent of the world’s cities are dealing with the impact of a changing climate, according to C40, a global network of cities committed to combating climate change. The connection between land use and climate change is clear.

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How land use impacts our climate

This massive research undertaking, which like past IPCC reports, collected and summarized thousands of reports and research papers by more than 100 scientists, examined how the land system interacts with climate.

During a press conference Wednesday, report authors discussed how they delved deeper into the way land use impacts the climate, and how climate in turn impacts activities such as food production. As the Earth’s biosphere gets warmer, evaporation increases, leading to drier conditions that increase the likelihood of wildfires and—without damper soil to moderate temperatures—heatwaves. As the planet becomes hotter and greenhouse gases in the atmosphere become more concentrated, the protein values in green crops, as well as the amount of micronutrients like zinc and iron, decline. These larger shifts in temperature and greenhouse gas concentration point to increased food insecurity and desertification unless better land use practices become widespread.

Much of the report focuses on agriculture, diet, and conservation, especially the need for farming practices to become more efficient and sustainable to avoid food shortages and further environmental degradation. Currently, 25 to 30 percent of total global food production is lost or wasted; merely lowering that number would cut down the demand for new farmland.

“Land use areas like agriculture, forestry, other ways we use the land, are responsible for about 13 percent of the carbon dioxide that we emit,” Luis Verchot, an IPCC author and researcher at the International Center for Tropical Agriculture, said during the press conference.

What does sustainable land use look like?

Going forward, the report suggests, we need to reformulate how our food system works and consider a calculated method of forestation and reforestation to help absorb more carbon dioxide.

Verchot said that sustainable land management covers a range of activities and disciplines, basically practices that don’t “degrade the productive capacity of the land.” That means areas like peatlands and wetlands are protected and not converted to other land use, that we’re protecting soil, maintaining soil organic matter, protecting water resources, and protecting “the integrity of the landscape.”

Cities have traditionally measured production emissions, or the emissions produced within city limits, to gauge their environmental performance. But to truly account for a city’s environmental footprint, one needs to measure consumption emissions, or those generated to support all activities or purchases within the city. That means cities need to not only change how they operate, and how people build, but think about the ways they do and don’t support efforts such as sustainable agriculture and zero-waste products.

Denser development that aims to reduce or restrict sprawl can play a key role in protecting and even expanding the types of landscape that act as natural carbon sinks, such as peatlands, forest lands, and coastal wetlands. Reforestation—especially in urban areas, where it provides shade and helps mitigate the urban heat island effect—and rethinking the food system are key. Cities should look at protecting whatever natural forests and landscapes they have, planting more trees where possible, and avoid adding more extensive paved surfaces, which can lead to more flooding. But pro-density development plans that limit the outward growth of urban areas to avoid destroying natural landscape should be a crucial, first step.